Governing apparatus



Patented Oct. 8, 1940 UNITED STATES PATENT OFFICE GOVERNING APPARATUS August Folgmann,-Falkensee, Kreis Ost-Havelland, Germany, assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application September 1, 1938, Serial No. 228,019

In Germany December 8, 1937 4 Claims.

I vention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig, l is a diagrammatic View of a known form of governing mechanism; and

Fig. 2 is a view partially in section, illustrating my invention.

In the drawing, there is illustrated, at ID, a relay governing mechanism for a prime mover, such as a turbine II, having a steam admission valve I2 operated by a piston I3, which is moved in a cylinder I4 as determined by the admission and exhaust of motive fluid to the latter under control of the pilot valve I6.

The piston I3 and the pilot valve I6 are connected to the lever II by pivots I9 and I8, respectively, the pivot I9 being located at one end of the lever I1 and the pivot I8 being arranged intermediately of the length thereof, and the other end of the lever is connected by pivot 2I to one end of the link 22. The other end of the link 22 is connected by the pivot 23 to one end of the lever 24, which, at an intermediate point, is connected by the pivot 25 to the collar 25a of the centrifugal governor 26 actuated by the prime mover, and it has its other end connected by a pivot 21 to the movable element or piston 28 of the differential pressure responsive device, at 29, the piston being arranged in the cylinder 3 I The piston 28 is moved due to relative variations in fluid pressures admitted to the cylinder 3| and at opposite sides of the piston by means of the passages 32 and 33 associated with the differential pressure producing device, at 34, the latter including a piston valve 35 controlling communication of a pressure supply port 34a with ports in communication with the passages 32 and 33. For a purpose to be described, the differential pressure responsive device, at 29, includes a load spring 28a effective to maintain a desired bias on the piston 28 in one direction.

The arrangement so far described is well known in the art and it operates as follows: A change in load is accompanied by a change in speed and the governor operates to move the collar 25a, thereby moving the lever 24 about the pivot 21, which remains fixed temporarily but which is adjusted, as hereinafter pointed out, to bring about a speed compensated adjustment of the mechanism. Movement of the lever 24 in consequence of governor movement moves the pilotvalve I6 and causes the operating piston I3 to move in one direction or the other, movement of the latter operating through the follow-up lever II to restore the pilot valve to neutral or cut-off position whereupon operation of the piston ceases.

The operation so far described is the standard one of a governing arrangement having a speed change or regulating percentage in going from no load to full load. Assuming an increase in load and consequent adjustment of the steam valve I2 to increase the admission of steam, the collar 25a of the governor would occupy a lower position to the extent of the decreasing speed m dent to increase in load, and this change in governor collar position is used to initiate actuation of the speedccmpensating arrangement for adjusting the steam admission for speed correction so as to restore the speed to a predetermined value, that is,'t0 secure isochronous operation. As already pointed out, the speed compensator comprises the difierential pressure developer, at 34, and the differential pressure responsive device, at 29. With downward movement of the governor collar 25a incident to increase in load, the piston valve 35 is moved downwardly so as to increase the pressure of fluid admitted to the cylinder 3| below the piston 28 relatively to the fluid pressure above the latter, in consequence of which the piston 28 moves upwardly until the force of the differential pressure is balanced by the force of the spring 2811. Upward movement of the piston 28 causes the pivot 21 to move upwardly to move the lever 24 about the pivot 25 acting as a fulcrum, the link 22 moving downwardly and the pilot valve I6 of the servo-motor or relay being operated to admit motive fluid below the operating piston I3 to open the steam valve I2 wider until sufficient steam is admitted to the turbine to restore the speed thereof to its normal or predetermined value. It will be observed that this speed compensating operation of the relay or servo-motor is initiated by movement of the pivot 21 due torelative pressure variation in the parts of the device, at 29; and this movement will continue until there is a sufficient additional change in steam admission to effect speed correction. It will be apparent that, due to the spring 28a, there will be a range of differential pressures for the range of movement.

of the piston 28, with the result that, for each prime mover load, the differential pressure force is changed sufiiciently,.due to governor movement, to bring about movement of the pivot 21 to such an extent that the servo-motor or operating cylinder may be operated to change the steam admission to effect speed correction, and, with completion of the speed correcting process, the servo-motor or operating cylinder occupies a neutral or cut-off position, the governor and its collar 250. are in normal position with the piston valve 35' in an intermediate or neutral position, and with the piston 28 of the differential pressure operating device moved sufficiently to effect the speed correction.

With an arrangement so far described, and illustrated in Fig. 1, the objection is encountered of deranged operation because of impurities present in the operating fluid; and, in order to prevent stoppage or undue restriction on account of impurities, it has been found necessary to make the clearances in the fluid passages much larger than is desirable for eflicient and accurate results. In accordance with the present invention, the differential pressure producing device, at 34, of Fig. 1 is replaced by the device at 34b and shown in Fig. 2.

The device shown in Fig. 2 is comprised mainly of a pair of interconnected displacement pumps arranged and operating in a manner hereinafter described. A pair of spaced gears 36 and 31 are mounted on parallel shafts 38 and 39, respectively, the gears and portions of the shafts being enclosed by a casing 4| providing bearings for the shafts, the latter having terminal portions 42 and 43 extending outwardly beyond a wall of the casing, for a purpose to be hereinafter described.

A driving gear 44 is disposed intermediately of the gears 36 and 3'! and meshes therewithjto provide a pair of gear pumps. The driving gear is carried by a shaft 46 extending outwardly beyond a wall of the casing, the outwardly extending portion carrying the gear 41 meshing with the gear 48 driven by the centrifugal governor 26.

The casing 4| is provided with fluid passages 5|, 52, 53 and 54 communicating with the two gear pumps, the passages 5| and 52 supplying fluid to the pumps, and the passages 53 and 54 discharging fluid therefrom. These discharge passages constitute outlets for the pumps and communicate with opposite sides of the cylinder 3|,through the passages 33 and 32 (Fig. 1).

The exposed terminal portions of the shafts 38 and 39 are respectively provided with circumferential recesses 56 and 51, communicating, through axial bores 58 and 59, respectively, with the discharge passages 53 and 54, the recesses 56 and 51 cooperating with edges 56a and 57a of a member 6| to provide overflow or spill ports or valves at the discharge or pressure sides of the displacement pumps.

The member 6| is' provided for varying, in reciprocal relation, the sizes of the overflow or spill ports, and is constituted by a block having spaced parallel cylindrical passages 62 and 63 extending therethrough and rotatably and slidably receiving the terminal portions 42 and 43 of the shafts 38 and 39 and provided with the edges 56a and 51a which cooperate with the recesses to provide the overflow or spill ports. The block 6| is so designed and constructed that when it is in a normal or centered position relative to the overflow or spill ports, each of the latter is partially uncovered to provide for a continuous flow of the fluid therethrough and the consequent prevention of clogging of the ports by foreign matter. If the block 6| is moved, cross-sectional areas of the spill ports will be changed in reciprocal relation, that is, as the cross-sectional area of one port is increased the area of the other port will be correspondingly decreased, and vice versa.

Provision is made for moving the block 6| in response to governor movement upon change in prime mover speed, such provision comprising, for example, a rod 66 secured to the block 6|, and extending through an axial bore 61 of the shaft 46, with its free end operatively engaged by the operating member or lever 24.

Provision also is made for manual adjustment of the block 6|. Accordingly, the rod 66 has a threaded connection with respect to a bushing 68 carried by the block, the upper free end of the rod being provided with a .hand wheel 69 for manual rotation of the rod to adjust the position of the block relatively to the governor lever.

It will-be apparent that movement of the block 6| in response to governor movement, will result in relative area variation of the spill ports or valves and uneven discharge at the pressure sides of the pumps, with a corresponding but op posite increase in pressure in the cylinder 3| above or below the piston 28, whereby desired speed-compensating movementof the operating member 24 will be effected.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In a control system for a prime mover having an admission valve-operated by a servo-motor whose piston valve is connected by linkage to a speed governor; a compensator connected to said piston valve by linkage, said compensator including a chamber having two compartments separated by a movable abutment member, a fluid pressure developer including a pair of displacement pumps, said pumps being of the gear type and including anintermediate gear common to both pumps and driven by the prime mover, a regulatable overflow for each pump at the discharge side thereof, passages connecting said pumps with the compensator compartments, movable means to vary the overflow of the pumps in opposite'directions and hence to vary the pressures in the passages likewise in opposite directions, means for moving the last-named means in response to governor movement, and means for manually adjusting the overflow of the pumps independently of the action of the governor.

2. Ina control system for a prime mover having an admission valve operated by a servo-motor whose piston valve is connected by linkage to a speed governor; a compensator connected to said piston valve by linkage, said compensator including a chamber having two compartments separated by a movable abutment member, a fluid pressure developer including a pair of displacement pumps, said pumps being of the gear type and including an intermediate gear common to both pumps and driven by the prime mover, a

regulatable overflow for each pump at the discharge side thereof, passages connecting said pumps with the compensator compartments, movable means to vary the overflow of the pumps 'in opposite directions "and hence to vary the pressures in the passages likewise in opposite directions, and means for moving the last-named means in response to governor movement, said passages being so constructed that when the discharge pressures are substantially equal there is a continuous flow of fluid through the pump overflows, whereby clogging is prevented.

3. In a control system for a prime mover having an admission valve operated by a servomotor whose piston valve is connected by linkage to a speed governor; a compensator connected to said piston valve by linkage, said compensator including a chamber having two compartments separated by a movable abutment member, a fluid pressure developer including a pair of displacement pumps having their outlets communicating with the compensator chamber, one at each side of the abutment member, said pair of pumps being comprised by a casing, a pair of spaced gears therein mounted on parallel shafts, a driving gear disposed intermediate said pair of gears and meshing therewith to provide, at the regions of intermeshing, a pair of gear pumps, fluid supply passages leading to the gear pumps and fluid discharge passages leading therefrom and constituting outlets, a pair of regulatable overflow ports in communication with the respective discharge passages, movable means for varying the size of the overflow ports in opposite directions whereby the pressures in the passages may be varied in opposite directions, and means for moving the last-named means in response to governor movement, said overflow ports being comprised by circumferential grooves on the parallel shafts and connected with the discharge passages by bores extending axially of the shafts, the means for varying the size of the overflow ports being comprised by a block surrounding and slidable longitudinally on the shafts to cover and uncover the ports.

4. In a control system for a prime mover having an admission valve operated by a servomotor whose piston valve is connected by linkage to a speed governor; a compensator connected to said piston valve by linkage, said compensator including a chamber having two compartments separated by a movable abutment member, a fluid pressure developer including a pair of displacement pumps having their outlets communicating with the compensator chamber, one at each side of the abutment member, said pair of pumps being comprised by a casing, a pair of spaced gears therein mounted on parallel shafts, a driving gear disposed intermediate said pair of gears and meshing therewith to provide, at the regions of intermeshing, a pair of gear pumps, fluid supply passages leading to the gear pumps and fluid discharge passages leading therefrom and constituting outlets, a pair of regulatable overflow ports in communication with the respective discharge passages, movable means for varying the size of the overflow ports in opposite directions whereby the pressures in the passages may be varied in opposite directions, and means for moving the last-named means in response to governor movement, said overflow ports and the means for varying the size thereof being so arranged that when the discharge pressures of the pumps are substantially equal there is a continuous flow of fluid through the overflow ports, whereby clogging is prevented.

AUGUST FOLGMANN. 

